Carbon dioxide charging apparatus and method for heat exchange unit

ABSTRACT

Apparatus and process to adsorb carbon dioxide onto compacted activated carbon in a HEU while removing the heat generated by the adsorption. A cooling tunnel is provided and maintained at approximately five degrees Celsius by continuously flowing a refrigerant therethrough. A plurality of completed cans with HEU are arranged internally and gassing heads are attached to each HEU and maintained at approximately 10-15 Bar for a period of twenty to thirty minutes after which the gassing heads would be removed and a new batch of cans inserted.

FIELD OF THE INVENTION

The present invention relates generally to a heat exchange unit for usein containers for self-chilling foods or beverages and more particularlyto the adsorption of carbon dioxide on compacted activated carbon foruse in a heat exchange unit of the type in which temperature reductionis caused by the desorption of the carbon dioxide from the compactedactivated carbon disposed within the heat exchange unit.

DESCRIPTION OF THE ART

Many foods or beverages available in portable containers are preferablyconsumed when they are chilled. For example, carbonated soft drinks,fruit drinks, beer, puddings, cottage cheese and the like are preferablyconsumed at temperatures varying between 33° Fahrenheit (0.555° Celsius)and 50° Fahrenheit (10° Celsius). When the convenience of refrigeratorsor ice is not available such as when fishing, camping or the like, thetask of cooling these foods or beverages prior to consumption is mademore difficult and in such circumstances it is highly desirable to havea method for rapidly cooling the content of the containers prior toconsumption. Thus a self-cooling container, that is, one not requiringexternal low temperature conditions is desirable.

The art is replete with container designs which incorporate a coolantcapable of cooling the contents without exposure to the external lowtemperature conditions. The vast majority of these containersincorporate or otherwise utilize refrigerant gases which upon release oractivation absorb heat in order to cool the contents of the container.Other techniques have recognized the use of endothermic chemicalreactions as a mechanism to absorb heat and thereby cool the contents ofthe container. Examples of such endothermic chemical reaction devicesare those disclosed in U.S. Pat. Nos. 1,897,723, 2,746,265, 2,882,691and 4,802,343.

Typical of devices which utilize gaseous refrigerants are thosedisclosed in U.S. Pat. Nos. 2,460,765, 3,373,581, 3,636,726, 3,726,106,4,584,848, 4,656,838, 4,784,678, 5,214,933, 5,285,812, 5,325,680,5,331,817, 5,606,866, 5,692,381 and 5,692,391. In many instances therefrigerant gas utilized in a structure such as those shown in theforegoing U.S. Patents do not function to lower the temperature properlyor if they do, they contain a refrigerant gaseous material which maycontribute to the greenhouse effect and thus is not friendly to theenvironment.

To solve problems such as those set forth in the prior art, applicant isutilizing as a part of the present invention an adsorbent-desorbentsystem which comprises activated carbon which functions as an adsorbentfor carbon dioxide. A system of this type is disclosed in U.S. Pat. No.5,692,381 which is incorporated herein by reference.

In these devices the adsorbent material is disposed within a vessel, theouter surface of which is in contact thermally with the food or beverageto be cooled. Typically, the vessel is connected to an outer containerwhich receives the food or beverage to be cooled in such a manner thatit is in thermal contact with the outer surface of the vessel containingthe adsorbent material. This vessel or heat exchange unit is affixed tothe outer container, typically to the bottom thereof, and contains avalve or similar mechanism which functions to release a quantity of gas,such as carbon dioxide which has been adsorbed by the adsorbent materialcontained within the inner vessel. When the valve is opened the gas,such as carbon dioxide, is desorbed and the endothermic process ofdesorption of the gas from the activated carbon adsorbent causes areduction in the temperature of the food or beverage which is in thermalcontact with the outer surface of the inner vessel thereby lowering thetemperature of the food or beverage contained therein.

To accomplish this cooling it is imperative that as much carbon dioxideas possible be adsorbed onto the carbon particles contained within theinner vessel and further that the thermal energy contained within thefood or beverage be transferred therefrom through the wall of the innervessel and through the adsorbent material to be carried out of the heatexchange unit along with the desorbed carbon dioxide gas. Preferably,the adsorbent material is activated carbon and the gas to be adsorbed iscarbon dioxide. In the context of this disclosure, “activated carbon”relates to a family of carbonaceous materials specifically activated todevelop strong adsorptive properties whereby even trace quantities ofliquids or gases may be adsorbed onto the carbon. Such activated carbonmay be produced from a wide range of sources, for example coal, wood,nuts (such as coconut) and bones and may be derived from syntheticsources, such as polyacrylonitrile. Various methods of activation exist,such as selective oxidation with steam, carbon dioxide or other gases atelevated temperatures or chemical activation using, for example, zincchloride or phosphoric acid. The adsorbent also includes a graphitematerial in an amount 0.01 to 80% by weight of the total composition,and a binder material.

Any available form of graphite, natural or synthetic, may beincorporated into the activated carbon, for example powdered or flakesof graphite may be used. Preferably, graphite is included in an amountranging from 10% to 50% by weight, more preferably 20% to 45% by weight,especially 40% by weight.

A binder material is included such as polytetrafluoroethylene, toachieve green strength of the formulation for further handling. Acomposition of activated carbon with graphite and a binder is disclosedin U.S. Pat. No. 7,185,511 which is incorporated herein by reference.

When the carbon dioxide under pressure is inserted into the heatexchange unit to be adsorbed onto the compacted adsorbent material, aphysical exothermic reaction occurs thereby releasing heat . As a resultof this exothermic reaction the compacted adsorbent material also heatsup and in so doing limits the amount of carbon dioxide which can beadsorbed onto the adsorbent material. To mitigate this problem, it hasin the past been necessary to charge the HEU with the pressurized carbondioxide in stages, that is, the carbon dioxide under pressure isinserted into the HEU until the compacted adsorbent material is nolonger capable of adsorbing the carbon dioxide. At this point the sourceof carbon dioxide under pressure is removed and the HEU is allowed tocool or alternatively is placed in a cooling tunnel which is maintainedat a very low temperature to dissipate the heat which has beengenerated. Obviously this creates a situation where mass production ofthe HEU is interfered with thus increasing the cost of production. Thereis thus a need for an apparatus and a method to charge the assembled HEUwith the carbon dioxide under pressure in such a manner that the heatgenerated by the exothermic reaction is removed during the time that thecarbon dioxide is being adsorbed onto the compacted adsorbent materialin the HEU.

SUMMARY OF THE INVENTION

Providing a source of containers adapted to receive a food or beverage,providing a source of heat exchange unit cans, filling the HEU cans withan adsorbent material, assembling the HEU can with the adsorbentmaterial to the container, inserting a plurality of the containers withthe HEU can assembled into a cooling tunnel, attaching a source ofcarbon dioxide under pressure to each of the plurality of the HEU's toinsert carbon dioxide into the HEU for adsorption on the compactedadsorbent material, maintaining the cooling tunnel at a predeterminedlow temperature for a predetermined period of time to remove the heatgenerated, removing the source of carbon dioxide from each of the HEUassemblies.

An apparatus for charging a heat exchange unit with carbon dioxidecomprising a conveyor bed for receiving a plurality of containers havinga heat exchange unit assembled therein, a plurality of gassing headcylinders, each connected to a source of carbon dioxide under pressure,means for attaching the gassing head cylinders to the HEU assemblies, asource of low temperature gas, means for circulating said lowtemperature gas to contact the conveyor assemblies.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing the method of the present invention;

FIG. 2 is a block diagram illustrating a specific portion of the methodas shown in FIG. 1;

FIG. 3 is a schematic diagram showing an assembled container and HEU;

FIG. 4 is a cross-sectional view of a puck for use in the method of thepresent invention; and

FIG. 5 is a schematic diagram of an apparatus for carbon dioxidecharging of a heat exchange unit while simultaneously removing the heatgenerated.

DETAILED DESCRIPTION

Referring now more particularly to FIG. 1, a schematic diagram has beenprovided of a manufacturing process line wherein the device is anendothermic device used to cool the contents of the container and moreparticularly where the container is a beverage can and an appropriatebeverage is to be inserted into the can after the HEU has been fullycharged. As is illustrated in FIG. 1, there is provided a can source 24which will contain a supply of beverage cans which will be thetraditional beverage can with the top end open since there will be nobeverage therein and the top must remain open for filling the can withthe beverage when the process of the present invention has beencompleted. The cans from the source 24 travel along an appropriateconveyor belt or the like 26 to a punching and flanging station 28. Thepunching and flanging station is utilized to provide an opening in thebottom of the can and to thereafter produce a flange around the openingprovided in the bottom of the can which may be used during the can HEUassembly process. There is also provided an HEU can source 30 whichcontains a source of containers utilized as an HEU in the self-chillingbeverage can industry. These cans have an open top and a closed bottomand are smaller than the beverage can from the source 24 so as to bereceivable therein while leaving sufficient space to accommodate thebeverage to be inserted later. The HEU cans will travel along anappropriate conveyor or the like 32 to an adsorbent filling station 34.The adsorbent filing station is utilized in accordance with onepreferred embodiment of the present invention, where the endothermicreaction is provided by the utilization of an adsorbent material whichis placed within the HEU can which, as will be described more fullybelow, later is caused to adsorb carbon dioxide which is retained andthen upon release and desorbtion provides the desired cooling function.In accordance with a preferred embodiment of the present invention, theadsorbent utilized will be activated carbon particles combined withgraphite and a binder which has been compacted. The open end of the HEUcan may be necked inwardly to mate with the punched and flanged open endof the beverage can subsequent to the HEU can being filled with theadsorbent material.

In any event, after the HEU can has been appropriately filled with theadsorbent material, it is then transported by the conveyor 36 to thecan/HEU assembly station 38. Also transported to the assembly station 38will be an appropriate valve and a gasket which is utilized in theassembly process. The valve and gasket are provided from a source 40thereof. The valve and gasket are transported by an appropriate conveyoror the like 42 to the can/HEU assembly station 38. In assembly of theHEU and affixing it to the beverage can an appropriate gasket formed ofelastomeric material is placed over the open end of the HEU whichcontains the adsorbent material therein. An inspection is performed toguarantee that the gasket is in fact seated properly upon the open endof the HEU. Subsequent thereto, the HEU open end having the gasketthereon is mated with the flange which surrounds the opening punchedinto the closed end of the can at the punching and flanging station 28.The valve and valve cup is then inserted into the opening provided inthe bottom of the can and simultaneously into the opening in the HEU canand by way of a crimping process the valve HEU and beverage can arepermanently secured together in a fashion so that an appropriate seal isformed between the HEU, the valve cup and the can to prevent any leakageof the beverage which is later to be placed into the beverage can. (Theassembled can and HEU are illustrated in FIG. 3 which will be describedin more detail below.)

Subsequent to the assembly of the beverage can and the HEU, thisassembly is transported by way of the conveyor belt or the like 44 to acooling tunnel 46 plus gassing station 50. As carbon dioxide is forcedunder pressure into the interior of the HEU can for adsorption anexothermic reaction occurs generating a substantial amount of heat whichwill radiate from the HEU. As the heat is generated from the carbondioxide adsorption process, the carbon naturally will heat up and as itheats up the amount of carbon dioxide which it can adsorb decreases. Atthe gassing station 50, which is an integral part of the cooling tunnel,the valve is depressed and carbon dioxide is inserted into the HEU untila predetermined pressure of approximately 25 bars is reached. Thecooling tunnel/gassing station will be filled with a cryogenic gas suchas liquid nitrogen or the like to maintain the cooling tunnel/gassingstation at a relatively low temperature, for example, on the order of 5°C. The source of carbon dioxide under pressure will remain affixed tothe HEU while the cooling tunnel/gassing station is held at the lowtemperature for a period of time to allow the twenty-five bar pressurein the HEU to be reached and maintained. The predetermined amount oftime to allow the desired amount of carbon dioxide to be adsorbed by thecompacted adsorbent will be approximately 20 to 30 minutes of time. Oncethe desired amount of carbon dioxide has been adsorbed onto thecompacted adsorbent, then the charged assembly 62 is transported byconveyor or other apparatus 60 to a desired position for filling withthe desired food or beverage.

By reference to FIG. 2, there is illustrated in more detail theadsorbent filling operation wherein the carbon powder is applied to theHEU can. As is shown in FIG. 2, there is provided a source of carbonpowder 68, a source of metal powder 70 and a source of binder 72. Thecarbon powder is transported by way of an appropriate conveyance meanssuch as a chute, chute belt, screw, plunger or other mechanism 74 to amixer station 76. The metal powder is also transported by a conveyancemeans 78 such as a belt, chute, screw or plunger to the mixer station 76and the binder is likewise transported by a similar appropriateconveyance mechanism 80 to the mixer station 76. At the mixer station76, the carbon powder and metal powder are intermixed with anappropriate binder to provide a desired mixture in a form which can beutilized to fill the HEU can. The utilization of the metal powder is toprovide an appropriate mix of metallic particles with the activatedcarbon particles to provide a better heat transfer through the carbonparticles, so that the heat of the beverage can be removed and exhaustedwith the carbon dioxide gas in a shorter period of time through thevalve. Although various metallic powder may work well, it has been foundthat graphite powder is preferred. Without some type of heat transfermechanism disposed within the carbon particles, it has been found thatthe heat is not easily transferred through carbon which is traditionallya relatively good insulator. Various types of heat sinks have beenutilized but it has been found that an appropriate mixture of the metalpowder with the carbon provides an excellent vehicle to transfer theheat from the beverage through the carbon and to the atmosphere. It hasbeen found that the metal powder and the carbon can be combined withouta binder and inserted into the HEU can and appropriately compacted withexcellent results in cooling the beverage. However, in a preferredembodiment, a binder such as polytetrafluroethylene is included with thecarbon and graphite. One embodiment of an appropriate composition isdisclosed in U.S. Pat. No. 7,185,511 which is incorporated herein bythis reference.

Referring now more particularly to FIG. 3, there is illustrated the canassembled with the HEU containing the compacted adsorbent. As is thereinillustrated, the can 112 has an interior open space 114 into which thedesired food or beverage will be deposited. The can 112 is open as shownat 116 for processing as described above in conjunction with FIGS. 1 and2. The HEU can 120 contains the compacted adsorbent 138. The HEU can 120is attached to the bottom of the can 112 through utilization ofappropriate crimping as is well known in the art. A valve 124 issupported on a valve cup 122 which is secured to the top of the HEU can120 as above described in conjunction with FIG. 1. The valve 124 extendsinwardly into the compacted adsorbent 138 as shown at 128. When theadsorbent is charged with the carbon dioxide under pressure, the gassinghead is attached to the valve 124 and the valve is opened by depressingthe plunger 130 to permit the carbon dioxide under pressure to enter theHEU can 120 and be adsorbed by the adsorbent 138.

FIG. 4 illustrates a puck which is utilized in the coolingtunnel/gassing station 46/50 as will be described more fully inconjunction with FIG. 5 herein below. The puck 140 is preferablyconstructed of a plastic material but may be constructed of metal orother materials as may be desired. The puck 140 includes a base 142which defines a groove 144 within which the open end 116 of the can 112is received. The base 142 of the puck may then be placed upon a conveyorbed or belt for movement from one station to another during the variousprocessing steps and specifically when the can HEU assembly is moved asindicated at FIG. 1 into the cooling tunnel/gassing station.

Referring now more particularly to FIG. 5, there is schematicallyillustrated, partly in cross section, an apparatus which will functionas the cooling tunnel/gassing station as above described in conjunctionwith FIG. 1. The apparatus as shown in FIG. 5 includes an enclosed areasuch as a tunnel 150 which is approximately three meters by two metersand includes a housing 152 which defines an internal portion 154 withinwhich the HEU/can are positioned to receive the carbon dioxide gas underpressure. The interior of the tunnel 150 is maintained at approximately5° C. by injecting a gas such as liquid carbon dioxide (CO₂) from asource 156 thereof into the interior 154 of the tunnel as illustrated bythe conduit 158. A flow of the liquid CO₂ into the interior 154 of thetunnel 150 will allow the HEU/can as shown in FIG. 3 to be initiallycooled.

The apparatus as shown in FIG. 5 includes a conveyor bed 160 upon whichthe HEU/can assemblies as illustrated at 162 can be positioned. As isshown, each of the HEU/can assemblies is positioned within a puck 164 ofthe type as shown in FIG. 4. As was above described and is nowillustrated in FIG. 5, the assembly as illustrated in FIG. 3 ispositioned on the puck by turning the assembly such that the open end116 of the can 112 is positioned within the groove 144 of the puck. Inthis position, the HEU/can assembly is disposed such that the valve 124extends upwardly as viewed in FIG. 5. A plurality of gassing headcylinders as shown at 166 are supported upon an index conveyor frame168. A source of carbon dioxide gas under pressure as shown at 170 isconnected to each of the gassing head cylinders 166 as indicated by theconduit 172.

The apparatus as shown in FIG. 5 may be operated in two differentmanners. In the first manner, the cans with the HEU's assembled thereinas shown at 162 and positioned within the pucks 164 are positioned sothat there are ten such HEU/can assemblies distributed across theconveyor bed 160 and there are twenty of these assemblies distributedlongitudinally along the conveyor bed 160. Thus the full index of twohundred HEU/can assemblies are loaded onto the conveyor bed andpositioned internally of the tunnel 150. As is viewed in FIG. 5, theconveyor bed would be pushed into the interior 154 and brought to restthere. When the cans are thus positioned within the interior 154 of thetunnel 150, each of the gassing heads 166 would be moved downwardly ontoeach of the assemblies independently depressing the plunger 130 and thusallowing the carbon dioxide gas under pressure from the source 170 toenter the HEU to start the adsorbtion of the carbon dioxide onto thecompacted adsorbent positioned therein. This application of the carbondioxide gas under pressure would be allowed to continue for a period ofapproximately twenty to thirty minutes at a gas pressure between 10 to15 bars for the entire period of time. During this time, the temperatureof the cans would increase as a result of the exothermic activitycreated by the carbon dioxide gas under pressure entering the HEU 120.After the full time out of the twenty to thirty minutes during whichperiod of time the heat being generated would be mitigated by thecontinuous flow of the liquid CO₂ blast from the source 156 thereof,thus allowing the CO₂ to be adsorbed in the desired amount by theadsorbent 138 in the HEU. After such has occurred all of the gassinghead cylinders 166 would be disengaged from the HEU/can assemblies 162and the conveyor bed would then move all of the two hundred cans out ofthe tunnel to then be transported to the desired position for furtherprocessing as above described. After such occurs, then the process asjust described would be repeated by indexing another two hundred cansonto the conveyor bed and repeating the process. As will be understoodby those skilled in the art, only one gassing cycle is thus needed foreach group of two hundred cans and approximately two hundred cans couldbe processed over each twenty to thirty minute period of time.

As an alternative arrangement, the apparatus as shown in FIG. 5 wouldfunction such that the conveyor bed 160 would be continuously movedthrough the tunnel 150 while the liquid CO₂ gas from the source 156 isprocessed through the interior 154 of the tunnel to maintain it at the5° C. As the HEU/can assembly within the puck as illustrated is thusmoved through the conveyor, gassing heads would be moved into engagementwith a row of the HEU/can assemblies, depressing the plunger 130 andallowing the carbon dioxide gas from the source 170 to enter the can.The cans with the gassing heads continuously in contact therewith andpermitting the carbon dioxide gas under pressure to be adsorbed by theadsorbent 138 would move through the tunnel over a period ofapproximately twenty to thirty minutes after which the gassing headcylinders would be removed from the row of the HEU/can assemblies. Sincethis is occurring on a continuous basis, the heat generated would bemuch less than that involved when the full two hundred cans are gassedsimultaneously. As a result, the process as just described would runmuch more efficiently and one can achieve the gassing of approximatelyten cans per minute.

Although the cooling tunnel plus gassing station has been illustrated inFIG. 1 as part of the inline manufacturing process, it should beunderstood that such is not required. The cooling tunnel plus gassingstation as illustrated in FIG. 5 may be a stand alone unit. In thiscase, the can/HEU assembly with the compacted adsorbent therein would bemanufactured separately wherever desired and then transported to thecooling tunnel plus gassing station to have the CO₂ under pressureinserted into the HEU. One advantage of such is to be able to ship theassembled can/HEU without the CO₂ thus making the units non-hazardousduring transport.

There has thus been disclosed a method and apparatus for achieving theassembly of an HEU containing an adsorbent with a can and the chargingof the HEU with carbon dioxide gas while mitigating the exothermicreaction created as a result thereof.

1. Apparatus for charging a heat exchange unit secured within a can forreceiving a food or beverage to be cooled, said heat exchange unithaving compacted adsorbent material therein, with a gas under pressurecomprising: a cooling tunnel; a source of refrigerant connected to saidcooling tunnel to maintain the temperature inside said cooling tunnel atapproximately five degrees Celsius; a conveyor bed for receiving aplurality of cans having said heat exchange unit therein movablypositioned within said cooling tunnel; a plurality of gassing headcylinders positioned to simultaneously engage at least a portion of saidheat exchange units to inject a gas under pressure into said at least aportion of said heat exchange units to be adsorbed by said compactedadsorbent material; a source of gas under pressure connected to saidplurality of gassing head cylinders; and said gassing head cylindersbeing connected to said at least a portion of said heat exchange unitsand injecting gas under pressure therein for a predetermined period oftime sufficient to fully charge said at least a portion of said heatexchange units with adsorbed gas under pressure.
 2. Apparatus as definedin claim 1 wherein said source of refrigerant is liquid carbon dioxide.3. Apparatus as defined in claim 2 wherein said gas under pressure iscarbon dioxide.
 4. Apparatus as defined in claim 3 wherein there is agassing head cylinder for each can having a heat exchange unit thereinpositioned on said conveyor bed and said conveyor bed with said gassinghead cylinders connected to said heat exchange units is maintainedstationary within said cooling tunnel for said predetermined time. 5.Apparatus as defined in claim 3 wherein said conveyor bed is movedthrough said cooling tunnel and said gassing head cylinders areconnected only to said at least a portion of said heat exchange unitsand injecting said carbon dioxide gas while being moved for saidpredetermined period of time.
 6. A method of charging adsorbent materialcontained within a heat exchange unit comprising: providing a pluralityof containers for received a food or beverage to be cooled; providing aplurality of heat exchange unit (HEU) cans containing a compactedadsorbent material therein; assembling an HEU can with each container;inserting the plurality of assembled containers into an enclosed area;attaching a source of carbon dioxide (CO₂) gas under pressure to eachHEU and continuously injecting CO₂ gas into said HEU for a predeterminedperiod of time for adsorption thereof by the adsorbent material;continuously flowing a refrigerant through said enclosed area to removeheat generated by the exothermic reaction of adsorption of the CO₂ gasfor a predetermined period of time to permit complete adsorption of theCO₂ gas by said adsorbent material; and removing said source of CO₂ gasfrom each HEU.
 7. A method as defined in claim 6 wherein the pressure ofsaid CO₂ gas is approximately 15 bars.
 8. A method as defined in claim 7wherein said predetermined time is between 20 and 30 minutes.
 9. Amethod as defined in claim 8 wherein the refrigerant is liquid CO₂ andsaid enclosed area is maintained at approximately five degrees Celsius.